Wednesday, January 7, 2015

Exactly a year to the date of last year's coldest arctic outbreak in the Charlotte region, another burst of polar air is spilling into the Carolinas on Wednesday.

An arctic cold front is expected to cross the immediate Charlotte area sometime around midday, and temperatures will tumble from around 40 degrees late Wednesday morning to 10 degrees by daybreak Thursday. And forecasters said there will be even colder readings in some places not far from Charlotte.

The good news, according to meteorologists, is that long-range guidance indicates the Carolinas might escape a messy ice storm early next week.

It was a year ago today when the temperature dropped to 6 degrees in Charlotte. It's not expected to get quite that cold Thursday morning, but readings at daybreak probably won't be too far from the record of 8 degrees for the date.

A wind chill advisory is in effect for Wednesday evening and early Thursday. Winds will gust up to 30 mph from late afternoon until around midnight, causing wind chills of 5 to 15 degrees. Forecasters said the winds will abate overnight, but they'll still be blowing at up to 10 mph, causing wind chills slightly below zero in Charlotte.

In the mountains, wind chill readings could tumble to 10 or 15 degrees below zero.

There are two threats from this cold -- the wind chills, which will be a problem from about 6 p.m. Wednesday until midday Thursday; and the prolonged cold, which will be a problem for water pipes and heating systems.

The polar outbreak will send temperatures below freezing in the Charlotte area from about midnight until shortly before noon Friday. Some areas above 3,500 feet might not get above freezing until Saturday.

Thursday's highs in Charlotte will only reach the upper 20s. Highs will be in the lower 40s Friday.

When temperatures are in the teens for many hours, as will be the case Thursday, frozen water pipes are the typical result. Be sure to keep water dripping from a faucet tonight. Plumbers say it's best to use the faucet farthest from where water enters the house.

Heating systems obviously will be seriously taxed. Assuming it's too late to get a system checkup on Wednesday, you might want to consider putting towels around window sills that leak cold air. And make sure electrical outlets are covered.

Another tip ... on Thursday, when the sun is shining, be sure to keep your blinds open on sunny sides of the house. Even though the temperature is in the 20s, the solar heat will help warm the inside of your residence.

Looking ahead to next week ...

Moisture is expected to arrive Sunday and intensify Monday, but the computer guidance can't agree on whether that will pose a threat of wintry precipitation for the Charlotte region.

The moisture is coming, the computer models agree. But they can't agree on the timing, and that's important. One strong high pressure system over New England will be moving out to sea Sunday, to be follow by another late Monday or Tuesday.

Two of the three most heavily used computer models predict the precipitation will arrive in the "gap" between the two cold high pressure systems. That means cold rain for the Charlotte region. The Global weather model predicts the precipitation will arrive with enough cold air still around for freezing rain Sunday.

The National Weather Service is leaning toward the cold rain scenario.

Tuesday, January 6, 2015

The late Woody Hayes, longtime Ohio State University football coach, used to say that three things can happen when you throw the football, and two of them are bad.

That's sort of what it's like when an arctic air mass moves into the Carolinas. As long as the cold is here, or even nearby, we're at risk of trouble.

The cold air -- our coldest of the season -- will arrive Wednesday afternoon. The wind will pick up, and temperatures will fall late Wednesday afternoon and evening from about 40 degrees into the teens. By Thursday morning, many spots in the Charlotte region will be sitting at 10 degrees.

It won't get above 30 degrees in most areas Thursday afternoon, and it'll drop into the teens again Friday morning.

A second arctic air mass will arrive late Friday or Saturday, and although the temperatures with the second system won't be quite as cold, they'll be cold enough to leave us at risk of trouble Sunday.

That's when a low pressure system off the Mexican coast could push eastward and begin affecting the Southeast.

One heavily used weather computer model, the Global, is predicting that the storm system, while weak, will spread precipitation into the Carolinas on Sunday morning. At that point, temperatures will be cold enough for freezing rain. I realize that some people enjoy wintry precipitation, but I don't think very many people want freezing rain. Power outages with temperatures in the 30s are not fun.

The other major weather computer model, the European, is predicting that the energy will remain over Baja California a bit longer and not reach the Carolinas until Sunday evening. By that time, the cold dome of high pressure over New England is expected to have moved offshore, and temperatures will climb enough so any precipitation falls as rain.

This is what we'll be watching over the next few days.

By the way, some of the longer-range computer guidance indicates the cold air will be reinforced early next week, and a fairly strong storm system will form off the Southeast coast. But that's more than a week away, and forecasts that far out are not terribly trustworthy.

Saturday, January 3, 2015

Charlotte-area weather will go through some weird twists and turns over the next 36 hours, but the big story is coming near the end of the week.

An arctic blast, featuring temperatures that are easily the coldest of the season, is poised to envelop the eastern United States and sink far into the South.

The cold air will arrive late Wednesday, as it now appears, and it will be a dry arrival -- no rain, no snow for the Piedmont.

The day of real change will be Thursday. Computer guidance on polar outbreaks is sometimes not extremely reliable, but if you believe what the computer models are forecasting, we might have a tough time climbing above freezing Thursday in Charlotte.

It will be windy, with wind chill temperatures probably at 10 degrees or lower for much of the day in the Charlotte region. That, of course, means we're looking at morning lows Thursday and Friday in the low to mid teens.

There is nothing to indicate at this point that the cold outbreak will be anything but dry. Humidity levels are forecast to be very low, and it would seem that we're talking about clear-blue skies and cold temperatures.

Computer guidance indicates the shot of cold air will be transient, with temperatures back in the 40s by Friday. But some bitterly cold air will be bottled over Canada, and it's not far-fetched to believe that another push of polar air will move into the Southeast early the following week.

About this blog

Steve Lyttle says growing up in northeastern Ohio, with its foot-deep snows and summertime severe thunderstorms, fueled his interest in meteorology. He has written about weather for 10 years at The Observer. Join the discussion about weather trends and weird weather events -- whether local or around the world.